Nuclear safety and security have always been of paramount importance. In the early 1960s, during the administration of John F. Kennedy, the decision was made to utilize the cryptographic technique of Permissive Action Links (PALs) to enhance the security of nuclear weapons. The primary objective was to prevent the unauthorized launch of US nuclear weapons by its European allies – including France, Germany, Turkey, and Greece – who were granted access to the US nuclear armaments through NATO agreements. Additionally, the adoption of PALs was prompted by apprehensions about a potential Soviet invasion of Western Europe. This could precipitate a nuclear conflict if US allies opted to deploy nuclear weapons without Washington’s authorization. This measure was conceived as a means to elevate the command and control protocols of nuclear weaponry, thereby diminishing the prospect of inadvertent or unauthorized launch.
The development of PALs was the joint responsibility of the US Department of Defense (DOD) and the Atomic Energy Commission (AEC), facilitated by the Sandia and Los Alamos National Laboratories working on US national security program. In 1962, the initial PALs were integrated with certain nuclear weapons stationed in Europe. This pivotal security measure gained global traction, with nuclear-armed nations worldwide adopting PALs to safeguard their weaponry. These PALs require a secret code or physical key to be entered before a nuclear weapon can be armed or launched. This code or key is encrypted and verified by a device on the weapon, preventing unauthorized access. This apparatus also establishes communication with other components within the weapon system, enabling their activation or deactivation. PALs have evolved from mechanical locks to complex electronic circuits, incorporating diverse cryptographic methods, including self-destruct protocols, tamper detection systems, and public-key encryption.
While PALs seemed highly secure in the past, nothing remains impervious. The advent of quantum computing has unveiled vulnerabilities in the military cryptography utilized to safeguard nuclear weapons. It is because the integrity of cryptography faces a challenge from quantum computing, as these advanced computers have the potential to break commonly used encryption techniques like RSA and elliptic curve cryptography. These techniques rely on complex mathematical puzzles that are difficult to solve by classical computers. Quantum computers, however, can employ algorithms such as Shor’s or Grover’s to efficiently crack these puzzles, leading to the decryption of encrypted data. This implies that if harnessed effectively, quantum computing could decrypt PALs, enabling access to nuclear weapons, including their launch codes.
The potential decryption of PALs guarding nuclear weapons presents a grave challenge to nuclear deterrence. If a state manages to develop and deploy a formidable quantum computer, it could potentially breach the encryption of PALs and other communication systems responsible for transmitting and verifying nuclear launch codes or directives. This scenario could grant the state unauthorized access, the ability to incapacitate, or even launch the nuclear weapons belonging to its adversaries clandestinely. This could provide the state with a substantial upper hand during a conflict, leveraging nuclear weapons for coercion, blackmail, or negotiation. The prevailing concept of nuclear deterrence hinges on the assurance that rational actors would refrain from initiating a nuclear conflict due to the promise of mutual devastation. Nevertheless, if quantum computing compromises nuclear weapons security, rational deterrence paradigm is challenged, thus escalating the risk of a catastrophic nuclear war.
What further exacerbates the situation is the fact that the strategic benefits arising from efficient quantum computing mechanisms have propelled states into a fierce arms race within this domain. Quantum computing could potentially revolutionize various domains vital for national security and military operations, such as intelligence, communication, cryptography, and simulation.
States have expressed concerns over the quantum development of other states, fearing that they could lose their competitive edge or technological sovereignty. Moreover, powerful states such as the US, Russia, and China, have launched aggressive quantum programs, investing heavily in quantum research and development and seeking to achieve quantum supremacy or dominance. These superpowers also compete for quantum talent, resources, and infrastructure and are developing quantum policies and strategies. Other states are also following them, trying to catch up or keep pace with the quantum race, or to establish their niche or role in the quantum landscape.
To counter the looming threat of nuclear deterrence vulnerability posed by quantum computing, states should proactively engage in research and policy formulation aimed at fortifying the security of their nuclear weapons. One avenue is the exploration of physical cryptographic methods, grounded in the intrinsic characteristics of radiation, as an alternative to digital encryption. These methods hold the potential to authenticate and verify nuclear warheads without divulging their sensitive design details while also being resistant to quantum attacks due to their departure from complex mathematical challenges.
It may be mentioned that physical cryptographic techniques are currently in the developmental phase and confront various technical and political obstacles before practical implementation. Consequently, it becomes imperative for states to channel investments into advancing these methods, fostering a collaborative environment with other nations to build trust, transparency, and mutual assurance in nuclear security.
About the Author
Ms Fatima Zainab is a student of Strategic and Security Studies at the National Defence University (NDU) Islamabad.
